This application claims the benefit of German patent application No. 199 62 296.5, filed Dec. 23, 1999, herein incorporated by reference.
The present invention relates to a bobbin winding machine with multiple winding heads, each of which includes a creel associated with a torque transmitter for controlling the bearing load between a bobbin held- in the creel and a driving drum, which torque transmitter can be adjusted by a drive element controlled by a winding-head computer connected to transmitters that detect the speed of the bobbin and the speed of the drive drum.
In a bobbin winding machine of the above-described type in which the creels are provided with a device corresponding to German Patent Publication DE 19 817 363 A1 the bearing load between the bobbin and the drive drum is exactly controlled over the entire course of bobbin winding. The bearing load is comprised of the combined weight of the bobbin and the creel together with the force resulting from the torque applied by the torque transmitter. The winding-head computer is connected to transmitters that detect the speed of the drive drum and the speed of the cross-wound bobbin. All moments that act on the creel can be calculated from these values, taking into consideration the density of the bobbin determined by the yarn tension and the yarn count. The bobbin control can then regulate the torque transmitter by regulating the drive element such that the desired bearing load or the desired course of the bearing load is exactly maintained.
It can occur during the operation of such a bobbin winding machine, especially during a batch change, that bobbins that are not yet entirely completed, i.e., so-called residual bobbins, are removed from a winding head and set into the creel of another winding head in order to be finished thereat. It can also occur at the end of a batch that a few winding heads are already turned off without the bobbins located therein having attained their full diameter. These residual bobbins are then removed and placed into the remaining winding heads which are still operating in order to be finished therein. As a rule, residual bobbins are also produced at the start of a new batch since the user makes attempts in this phase with different cross-wound bobbin diameters, correction factors, etc., to achieve a bobbin that is optimal for the current application. It is likewise important in adjusting of the automatic bobbin changer to present several full bobbins to a winding head in order to adjust the bobbin changing device with these full bobbins.
Problems can result with the processing of residual bobbins in bobbin winding machines of the above-described type. On the one hand, the bearing load between the bobbin and the drive drum is not correct. On the other hand, it is hardly possible to replace an empty tube with a larger bobbin since the creel has been automatically brought into the position associated with an empty bobbin tube. In order to be able to operate in an exact manner, the diameter and the amount of wound-on yarn of a residual bobbin would have to be entered into the winding-head control in order to suitably adjust the position of the creel for this residual bobbin. However, this is not practical because, on one hand, these values are usually not known and, on the other hand, there is also no possibility at the individual winding heads of entering this data.
The present invention therefore has the objective of developing a bobbin winding machine of the initially mentioned type in such a manner that the processing of residual bobbins does not pose any problems, that is, that even residual bobbins with a fairly large diameter instead of empty tubes can be placed into a creel and thereafter the bearing load between bobbin and drive drum corresponds at least approximately to the desired course of winding.
This problem is addressed by providing means that can be actuated by an operator for adjusting the drive element and therewith the creel for adaptation to the diameter of the residual bobbin inserted into the creel. The winding head computer calculates the torque to be applied by the torque transmitter using information representing the density of the residual bobbin and information resulting from the adaptation to the diameter of the residual bobbin about the position of the creel before the start of the winding process and controls its drive element accordingly.
In this manner, it is possible for the operator to move the creel into a position that is suitable for the residual bobbin to be inserted, that is, that corresponds at least approximately to its diameter. From this position, the required bearing load is calculated within certain permissible tolerances and, given when the winding head is put in operation, taking into consideration the bobbin density that is known at least to the central computer of the bobbin winding machine and transmitted to the winding head computer. After the winding head has started to run, the winding head computer then calculates, based on the bobbin speed that is now detected in relationship to the speed of the drive drum, the precise bobbin diameter and exactly calculates the weight via the density of the bobbin so that the bearing load is exactly determined thereafter.
A position of the creel that substantially corresponds exactly to the diameter of the residual bobbin can be brought up in an automatic manner with an embodiment of the bobbin winding machine in which the winding-head computer is set such that, after actuation of the afore-described adjusting means, a lifting of the creel initially takes place and at the start of the lowering process of the creel, the drive drum is put into a rotary motion at a low speed. At the start of a detected rotation of the residual bobbin brought about by the drive drum, a control signal is generated that controls the end of the adjusting process for the adaptation to the diameter of the residual bobbin and also initiates the ending of the low speed rotary motion of the drive drum. The speed is advantageously set in such a manner that the surface velocity of the drive drum is approximately 50 m/min, which prevents damaging of the residual bobbin.
Further features and advantages of the invention will be understood from the following description of an exemplary embodiment shown in the accompanying drawing.